
%list(usable).
-P(i(?x,?y)) | -P(?x) | P(?y).
%end_of_list.

%list(sos).
P(i(i(?x,?y),i(i(?y,?z),i(?x,?z)))).  % CN1
P(i(n(?x),i(?x,?x))).                      % CN2
P(i(?x,i(n(?x),?y))).                      % CN3
%end_of_list.

%list(passive).
%-P(i(a,a)). % | $Ans(CN_16).
%-P(i(b,i(a,b))). % | $Ans(CN_18).
-P(i(i(i(a,b),c),i(b,c))).% | $Ans(CN_19).
%end_of_list.
